Pardon my ignorance... So people actually connect mice and keyboards to the deck? How does that work in terms of playing position? I thought the deck is mostly targeted towards mobile players who will have it on a bed, chair etc where there won't be any surfaces for using a mouse or other peripherals.
SO you can do what I'm currently doing because I'm in the middle of moving countries and my desktop isnt here!
I have a monitor i'm borrowing from work, a mouse, keyboard, and the steamdeck Dock. And I just treat it like a desktop. You can still easily use steam big picture mode. OR you can boot to desktop, as the Steamdeck is just a Arch linux install. Its honestly amazing.
Like the other poster, I use the SD for convenience, snatching 10 minutes of gameplay wherever I am and whenever I have time, and that means not plugging anything in.
But the SD is just a PC in a handheld form factor. You can plug in a dock, external monitor and other peripherals, only removing it when travelling, if that suits you.